Method of restoring blood flow through an obstructed blood vessel of the brain

ABSTRACT

An acute stroke recanalization system and processes include catheter-based improved reconstrainable or tethered neurological devices which are deliverable through highly constricted and tortuous vessels, crossing the zone associated with subject thrombi/emboli, where deployment impacts, addresses or bridges the embolus, compacting the same into luminal walls which enables perfusion and lysis of the embolus, while the improved neurological medical device itself remains contiguous with the delivery system acting as a filter, basket or stand alone stenting mechanism, depending on the status of the embolus and other therapeutic aspects of the treatment being offered for consideration.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.12/123,390, filed May 19, 2008, which claims priority to, andincorporates expressly by reference U.S. Provisional Application Ser.No. 60/980,736, filed Oct. 17, 2007; U.S. Provisional Application Ser.No. 61/044,392, filed Apr. 11, 2008; U.S. Provisional Application Ser.No. 61/015,154, filed Dec. 19, 2007; U.S. Provisional Application Ser.No. 60/989,422, filed Nov. 20, 2007; U.S. Provisional Application Ser.No. 60/987,384, filed Nov. 12, 2007; and U.S. Provisional ApplicationSer. No. 61/019,506, filed Jan. 7, 2008; each as if fully set forthherein.

BACKGROUND OF THE INVENTION

The present disclosure relates to minimally invasive and catheterdelivered revascularization systems for use in the vasculature,especially those suited for usage above the juncture of the SubclavianArtery and Common Carotid Artery. In particular, this disclosure relatesto revascularization devices for use in treatment of ischemic stroke,including improved neurological medical devices which are tethered orreconstrainable self-expanding neurological medical devices.

SUMMARY OF THE INVENTION

According to embodiments of the present invention, there are disclosedacute stroke revascularization/recanalization systems comprising, incombination; catheter systems having guidewires to access and emplaceimproved neurological medical devices into the cerebral vasculature, thesystems including proximal stainless steel pushers with distal nitinoldevices or one-piece nitinol devices. In some embodiments, the systemscomprise a polymeric liner incorporated within the pusher to improvetrackability of the guidewire. In some embodiments, the polymeric linerextends beyond the distal tip of the pusher for guiding the guidewireand preventing entanglement in the nitinol device.

According to embodiments, there are disclosed one-piece nitinol devicesin combination with the above disclosed and/or claimed catheter systems.

Briefly stated, according to embodiments a novel enhanced tetheredrevascularization device is deliverable through highly constricted andtortuous vessels, entering a zone associated with subjectthrombi/emboli, where deployment impacts the embolus, compacting thesame into luminal walls which enables perfusion and lysis of theembolus, while the revascularization device itself remains continuouswith the delivery system acting as a filter, basket or stand alonerevascularization mechanism, depending on the status of the embolus andother therapeutic aspects of the treatment being offered forconsideration.

According to embodiments of the system and processes of the presentinvention, in certain iterations, once deployed the instant systemcompacts the embolus against the luminal wall, creating a channel forblood flow which may act like a natural lytic agent to lyse or dissolvethe embolus.

According to embodiments, there is provided an improved neurologicalmedical device which comprises, in combination, a catheter systemeffective for delivering a combination radial filter/revascularizationdevice and basket assembly into a desired location in the cerebralvascular system, a self-expanding radial filter/revascularization deviceand basket assembly detachably tethered to the catheter system whichfunctions in at least three respective modes, wherein the radialfilter/revascularization device and basket assembly is attached to thecatheter and wherein radial filter/revascularization device and basketassembly further comprises at least two states per mode, a retractedstate and an expanded state; and wherein the radialfilter/revascularization device and basket assembly may retracted intothe retracted state after deployment in an expanded state, in each mode.

According to embodiments, there is provided a process comprising incombination providing a revascularization device tethered to a catheterby emplacing the system into a patient for travel to a desired locationin a vessel having an obstruction/lesion and deploying therevascularization device by allowing it to move from a first state to asecond state across a lesion which compresses the subject embolus into aluminal wall to which it is adjacent whereby creating a channel forblood flow as a lytic agent, and removing the system which theobstruction/lesion is addressed.

It is noted that if blood flow does not lyse the blood embolus, lyticagents can be administered via the guidewire lumen, as a feature of thepresent invention.

According to embodiments, there is provided a process whereby therevascularization device tethered to a catheter functions as a radialfilter to prevent downstream migration of emboli.

The U.S. Food and Drug Administration (FDA) has previously approved aclot retrieval device (The Merci® brand of retriever X4, X5, X6, L4, L5& L6: Concentric Medical, Mountain View, Calif.). Unfortunately, whenused alone, this clot retriever is successful in restoring blood flow inonly approximately 50% of the cases, and multiple passes with thisdevice are often required to achieve successful recanalization. IAthrombolytics administered concomitantly enhance the procedural successof this device but may increase the risk of hemorrhagic transformationof the revascularization infarction. There have been several reports ofcoronary and neuro-stent implantation used for mechanical thrombolysisof recalcitrant occlusions. In summary, stent placement withballoon-mounted or self-expanding coronary and neuro-types of stents hasbeen shown to be an independent predictor for recanalization of bothintracranial and extra cranial cerebro-vasculature occlusions. Thisprovides some insight into approaches needed to overcome theselongstanding issues.

By way of example, self-expanding stents designed specifically for thecerebro-vasculature can be delivered to target areas of intracranialstenosis with a success rate of >95% and an increased safety profile ofdeliverability because these stents are deployed at significantly lowerpressures than balloon-mounted coronary stents. However, systems usingthis data have yet to become commercial, available or accepted by mostpractitioners.

The use of self-expanding stents is feasible in the setting ofsymptomatic medium—and large-vessel intracranial occlusions. With stentplacement as a first-line mechanical treatment or as a “last-resort”maneuver, TIMI/TICI 2 or 3 revascularization can be successfullyobtained, according to clinical data now available.

The literature likewise suggests that focal occlusions limited to asingle medium or large vessel, particularly solitary occlusions of theMCA or VBA, may be preferentially amenable to stent placement and thuscan help clinicians to achieve improved rates of recanalization. Inaddition, gender may play a role in the success of self-expanding stentimplementation. However, systems need to be designed to execute on this.

Despite increasing utilization of prourokinase rt-PA (recombinant tissueplasminogen activator) or other antithrombotic agents (e.g., Alteplase®and Reteplase®), recanalization rates remain approximately 60%. Themajor concerns with pharmacologic thrombolysis (alone) has been the rateof hemorrhage, inability to effectively dissolve fibrin\platelet-richclots, lengthy times to recanalization, and inability to prevent abruptreocclusions at the initial site of obstruction. In PROACTII, ICH withneurologic deterioration within 24 hours occurred in 10.9% of theprourokinase group and 3.1% of the control group (P=0.06), withoutdifferences in mortality. Abrupt reocclusions or recanalized arterieshas been found to occur relatively frequently, even with the addition ofangioplasty or snare manipulation for mechanical disruption of thrombus,and seems to be associated with poor clinical outcomes.

The use of other mechanical means has been reported to be effective inrecanalization of acute occlusions. It makes sense that a combination ofmechanical and pharmacologic approaches would yield greater benefit.

A known investigation in an animal model has shown, both the Wingspan®brand of self-expanding stent and Liberte® brand of balloon-mountedstent (Boston Scientific, Boston, Mass.) were able to re-establish flowthrough acutely occluded vessels. The self-expanding stents performedbetter than the balloon-mounted stents in terms of navigability to thetarget site. The self-expanding stents incurred lower rates of vasospasmand side-branch occlusions, which suggests superiority of these stents,over balloon-mounted stents, to maintain branch vessel patency duringtreatment of acute vessel occlusion. In a previous animal studiesconducted, intimal proliferation and loss of lumen diameter were seenafter the implantation of bare-metal, balloon-expandable stents. Theliterature further supports this set of issues.

These phenomena are believed to be attributable to intimal injurycreated during the high-pressure balloon angioplasty that is requiredfor stent deployment.

Compared with coronary balloon-mounted stents, self-expanding stentsdesigned for use in the intracranial circulation are superior becausethey are easier to track to the intracranial circulation and safer todeploy in vessels in which the true diameter and degree of intracranialatherosclerotic disease are unclear.

Moreover, based on previous experience, currently availableself-expanding stents provide enough radial outward force at bodytemperature to revascularize occluded vessels, with low potential forthe negative remodeling and in-stent restenosis that are associated withballoon-mounted stents in nonintracranial vascular beds.

Because self-expanding stents are not mounted on balloons, they are themost trackable of the stents currently available for the intracranialcirculation. Unlike clot retrievers, which lose access to the target(occlusion site) every time they are retrieved (and often to necessitatemultiple passes), self-expanding stents allow for wire access to theocclusion at all times, increasing the safety profile of the procedureby not requiring repeat maneuvers to gain access to the target site (asin the case for the Merci® brand of clot retriever).

Self-expanding stent placement of acute intracranial vessel occlusionsmay provide a novel means of recanalization after failure of clotretrieval, angioplasty, and/or thrombolytic therapy. The patency ratesin this series are encouraging, yet issues remain to be addressed.

In the setting of acute stroke, restoring flow is of singularimportance. In-stent stenosis or delayed stenosis may be treated in adelayed fashion on an elective basis, should the patient achieve afunctional recovery from the stroke.

Recanalization with self-expanding stents may provide flow through thepatent artery, and restore flow to the perforators, or, alternatively,they may remain occluded. Restoring flow to the main artery, however,will reduce the stroke burden. What is needed is a solution leveragingpositive aspects of stent-based treatment without the negative outcomeswhich have been associated with traditional stenting.

DRAWINGS OF THE INVENTION

The above-mentioned features and objects of the present disclosure willbecome more apparent with reference to the following description takenin conjunction with the accompanying drawings wherein like referencenumerals denote like elements and in which:

FIG. 1 is a perspective view of an embodiment of an acute strokerecanalization system according to embodiments of the present disclosurein a first configuration; and

FIG. 2 is a perspective view of an embodiment of an acute strokerecanalization system according to embodiments of the present disclosuretailored for use with the neurovasculature in a second configuration,further illustrating modular aspects of the system as used with tetheredor reconstrainable self-expanding neurological medical devices.

FIG. 2A illustrates a detailed view of the inner catheter of FIG. 2.

FIGS. 3A-3D illustrate an embodiment of an inner catheter of the acutestroke recanalization system of FIGS. 1 and 2.

FIGS. 4A-4C illustrate a perspective view, a side view, and a frontview, respectively, of an embodiment of a self-expandingrevascularization device.

FIG. 5 illustrates an embodiment of a stroke device.

FIG. 6 shows a schematic of a delivery system and exemplary iteration ofa temporary tethered stent mechanism according to the presentdisclosure.

FIG. 7 likewise schematically depicts a delivery system with embodimentsof a tethered stent for use with an over-the wire guidewire system.

FIGS. 8A-8D illustrate an embodiment of a revascularization deviceconfigured for eccentric coupling to a pusher.

DETAILED DESCRIPTION OF THE INVENTION

The present inventors have realized that by leveraging a conventionalself-expanding revascularization device delivery platform, a poly-modicsystem can be iterated which impacts, addresses and/or crosses anembolus, radially filters, and either removes the offending embolus oris optionally emplaced to address the same. A paucity of extant systemseffective for such combination therapies is noted among the art.

Using endovascular techniques self-expandable tethered orreconstrainable self-expanding neurological medical devices offerinstant revascularization/recanalization of MCAs and related vessels,without any of the traditional concerns associated with stenting,according to embodiments of the present invention.

Expressly incorporated herein by reference are the following U.S.Letters patents and publications, each as if fully set forth herein:2005/0119684; 2007/0198028; 2007/0208367; U.S. Pat. Nos. 5,449,372;5,485,450; 5,792,157; 5,928,260; 5,972,019; 6,485,500; 7,147,655;7,160,317; 7,172,575; 7,175,607; and 7,201,770.

The instant system allows for natural lysis, revascularization of thechallenged vessels, and importantly radially filters any particulatesgenerated, to obviate the need to be concerned with distal migration ofthe same, unlike prior systems or applications which include largely“off-label” usages of devices approved only for aneurysms in the brain.

The present disclosure relates to revascularization devices used totreat, among other things, ischemic stroke. Naturally, therefore, therevascularization devices of the present disclosure are designed to beused in neuro-type applications, wherein the specifications of thepresent catheters and revascularization devices may be deployed in theblood vessels of the cerebral vascular system. Similarly contemplatedfor the revascularization systems and catheters of the presentdisclosure is deployment in other parts of the body wherein thespecifications of the present disclosure may be used in other vessels ofthe body in a non-invasive manner.

According to embodiments, disclosed herein is a catheter-basedrevascularization system. The revascularization devices of the presentdisclosure are for revascularization of blood vessels. When thecatheter-based revascularization system of the present disclosure isdeployed into a blood vessel having an embolus, the revascularizationdevice is expanded thereby opening the vessel so that the vessel canresume proper blood flow.

According to the instant teachings, deployment of the system of thepresent disclosure, establishes immediate 50% of the diameter of thelumen patency of the vessel being addressed. Among the prior art, nosystem having adequately small profile with flexibility to promoteimproved access for in-site treatment is known which may be used as atemporary (not implanted) solution. Those skilled in the art readilyunderstand that detachment methods comprising mechanical, electrical,hydraulic, chemical, or thermal, and others are within the scope of theinstant teachings.

Moreover, as the embolus dissolves, either via blood flow or by infusinglytic agents than the guidewire lumen, the deployed revascularizationdevice radially filters larger embolus particles from travelingdownstream, thereby reducing the chances of further complications. Oncethe blood vessel is revascularized, the revascularization device ismodified to be in a removable state together with filtered detritus, andthe catheter-revascularization system is removed from the blood vesselsof the patient.

Likewise, in the event that no resolution of the embolus is noted in theinstant revascularization system the inventors contemplate detachmentand employment as a stent of the cage-like membrane. Angiographicrecanalization has been associated with improvement in clinical outcomein the setting of acute stroke resulting from acute intracranialthrombotic occlusion. Anatomic limitations (tortuous anatomy, length ofthe occlusion, or location of occlusion) or supply limitations are amongthe reasons precluding use of prior art systems until the advent of theinstant teachings.

Stenting has been used successfully to restore flow after abruptreocclusion occurring after recanalization with other modalities inprevious cases. Stenting has also been reported in cases in which othermodalities have failed to recanalize vessels. Even if an underlyingstenosis is rarely the cause of stroke, stenting may play a role bymorselizing the embolic clot or trapping it against the arterial wall.In several embodiments, the present invention comprises an acute strokerevascularization process that comprises providing a reconstrainableself-expanding microstent system, deploying a self-expanding microstentwithin a neurological vessel; achieving at least one ofrevascularization and recanalization of a subject vessel; and removingthe self-expanding microstent. In some embodiments, at least onesupplemental therapy is also provided, and comprises one or more of thefollowing: pharmacological thrombolytic agents, intraarterialthrombolytics, and mechanical manipulation.

The use of intracranial stents as a method for arterial recanalizationduring cerebral ischemia caused by focal occlusion of an intracranialvessel has been demonstrated to have benefits in some cases. Despite theuse of available pharmacological and mechanical therapies, angiographicrecanalization of occluded vessels has not been adequately achievedbefore stent placement, in most cases.

When SAH and intracranial hematoma occurred in patients in whomballoon-mounted stents were used, they most likely resulted from distalwire perforation. The distal wire purchase needed to navigate a coronarystent into the intracranial circulation may explain the occurrence ofthese adverse events. Alternatively, multiple manipulations of theMerci® brand of retriever device or expansion of balloon-mounted stentsmay have induced microdissections in the vessel. Stents designed forintracranial navigation have better navigability and pliability. TheWingspan® brand of stent (Boston Scientific) was designed to have moreradial force than the Neuroform® brand of stent and may further improvethis technique. However, the act clearly needs to advance further inthis area.

IA therapy for stroke has evolved during the past decade. Approval ofthe Merci® brand of retriever device represents a significant steptoward achieving better outcomes in acute stroke for patients notsuitable for IV tPA. However, recanalization is not always achievedusing this device. Therefore, additional treatment options are required,as offered for consideration herein.

Spontaneous dissection of the internal carotid artery (ICA) is one ofthe main causes of ischemic stroke in young and middle-aged patients,representing 10% to 25% of such cases. Because infarct due to dissectionis mainly thromboembolic, anticoagulation has been recommended toprevent new stroke in patients with acute dissection, provided they haveno contraindications. In the acute phase, intravenous recombinanttissue-type plasminogen activator (IV rtPA) given within 3 hours afteronset of stroke due to dissection is reportedly safe and effective.However, this often needs supplemental therapy to be effective.

Endovascular treatment with stent deployment for ICA dissection withhigh-grade stenosis or occlusion may be most appropriate whenanticoagulation fails to prevent a new ischemic event. In such cases,the MCA may be patent. However, to compare outcomes of patients withacute stroke consecutive to MCA occlusion due to ICA dissection treatedeither by stent-assisted endovascular thrombolysis/thrombectomy or by IVrtPA thrombolysis. Stent assisted endovascular thrombolysis/thrombectomycompared favorably with IV rtPA thrombolysis, underscoring the need forthe instant device.

The main limitation of this procedure is the immediate need for anexperienced endovascular therapist. The number of cases of MCA occlusiondue to carotid artery dissection was quite small and represented <10% ofpatients admitted for carotid dissection. However, despite thesepromising preliminary results, potential drawbacks related to theprocedure must be considered. Acute complications such as transientischemic attack, ischemic stroke, femoral or carotid dissection, anddeath have been reported. Other potential hazards of endovasculartreatment of carotid dissection could have been observed. On balance,the risk-benefit favors solutions like the present invention.

Most patients with acute cerebrovascular syndrome with MC occlusionconsecutive to ICA dissection have poor outcomes when treated withconventional IV rtPA thrombolysis, whereas most patients treated withstent-assisted endovascular thrombolysis/thrombectomy show dramaticimprovements. Further large randomized studies are required to confirmthese data, which trends likewise are technical bases for the instantsystems.

According to embodiments and as illustrated in FIG. 1, catheter-basedrevascularization system 100 provides a platform for lysing emboli inoccluded blood vessels. Accordingly, catheter-based revascularizationsystem 100 generally comprises control end 102 and deployment end 104.According to embodiments, control end 102 is a portion of the devicethat allows a user, such as a surgeon, to control deployment of thedevice through the blood vessels of a patient. Included as part ofcontrol end 102 is delivery handle 106 and winged apparatus 108, in someembodiments. Those skilled in the art readily understand module 113 (seeFIG. 2) is detachable.

According to some examples of the instant system during shipping ofcatheter-revascularization system 100, shipping lock (not shown) isinstalled between delivery handle 106 and winged apparatus 108 toprevent deployment and premature extension of revascularization device124 (see FIG. 2) while not in use. Furthermore, by preventing deliveryhandle 106 from being advanced towards winged apparatus 108, coatingsapplied to revascularization device 124 are stored in a configurationwhereby they will not rub off or be otherwise damaged whilecatheter-based revascularization system 100 is not in use.

According to embodiments, agent delivery device 130 provides a conduitin fluid communication with the lumen of the catheter-basedrevascularization system 100 enabling users of the system to deliveragents through catheter-revascularization system 100 directly to thelocation of the embolus. The instant revascularization system deliverydevice may be made from materials known to artisans, including stainlesssteel hypotube, stainless steel coil, polymer jackets, and/or radiopaquejackets. In one embodiment, the revascularization systems comprise aplurality of apertures 118 allowing infusable lytic agents to exitradially and distally into at least a subject embolus when transmittedthrough agent delivery device which is in fluid communication therewith.The revascularization systems according to several embodiments hereincan comprise radiopacity for imaging purposes.

Accordingly, luer connector 132 or a functional equivalent providessterile access to the lumen of catheter-based revascularization system100 to effect delivery of a chosen agent. Artisans will understand thatrevascularization devices of the present invention include embodimentsmade essentially of nitinol or spring tempered stainless steel.Revascularization devices likewise may be coated or covered withtherapeutic substances in pharmacologically effective amounts orlubricious materials. According to embodiments, coatings includenamodopene, vasodialators, sirolamus, and paclitaxel. Additionally, atleast heparin and other coating materials of pharmaceutical nature maybe used.

Deployment end 104 of catheter-based revascularization system 100comprises proximal segment 110 and distal segment 120. Proximal segment110, according to embodiments, houses distal segment 120 and comprisesouter catheter 112 that is of a suitable length and diameter fordeployment into the blood vessel of the neck, head, and cerebralvasculature. For example in some embodiments, proximal segment 110 isfrom at least about 100 cm to approximately 115 cm long with an outerdiameter of at least about 2.5 French to about 4 French.

Referring also to FIG. 2, distal segment 120 comprises inner catheter122 and revascularization device 124 (as shown here in one embodimenthaving uniform cells, variable cells likewise being within otherembodiments of the present invention), which is connected to innercatheter 122. Inner catheter 122, according to embodiments, is made fromstainless steel coil, stainless steel wire, or ribbon or laser cuthypotube and is of a suitable length and diameter to move through outercatheter 112 during deployment. For example, inner catheter 122 extendsfrom outer catheter 112 38 cm, thereby giving it a total length ofbetween at least about 143 and 175 cm. The diameter of inner catheter122 according to the exemplary embodiment is 2.7 French, with an innerdiameter of at least about 0.012 to 0.029 inches. The inner diameter ofinner catheter 122 may be any suitable diameter provided inner catheter122 maintains the strength and flexibility to both deploy and retractrevascularization device 124. In one embodiment, an inner catheter 122′comprises a variable-pitch hypotube, as shown in FIGS. 3A-D. In oneembodiment, the inner catheter 122′ comprises a laser-cut,variable-pitch hypotube. Region L comprises a laser cut transitionregion of the variable-pitch hypotube. Regions P1, P2 and P3 comprisethree regions of the variable-pitch hypotube having variable pitch. Inone embodiment, the pitch decreases from region P1 to region P2 and fromregion P2 to region P3.

Referring to both figures, revascularization device 124 is aself-expanding, reconstrictable retractable device tethered to innercatheter 122. Revascularization device 124 may be made from nitinol,spring tempered stainless steel, or equivalents as known and understoodby artisans, according to embodiments. Revascularization device 124,according to embodiments and depending on the particular problem beingaddressed, may be from at least about 3.5 mm to about 50 mm in itsexpanded state. In an expanded state, revascularization device 124 isdesigned to expand in diameter to the luminal wall of blood vessel whereit is deployed.

As known to artisans, revascularization device 124 may be coated orcovered with substances imparting lubricous characteristics ortherapeutic substances, as desired. Naturally, the expandable meshdesign of revascularization device 124 must be a pattern whereby whenrevascularization device 124 is retracted, it is able to fully retractinto inner catheter 122. The nature of the cell type likewise changeswith respect to the embodiment used, and is often determined based uponnature of the clot.

In one embodiment, a revascularization device 124′ comprises a pluralityof struts 127 and a plurality of open cells 129, as shown in FIGS.4A-4C. In accordance with some embodiments, recapturability, flexibilityand tracking are enabled by the struts of the revascularization device124′, which permit flexion and extension to navigate through curvedvessels. FIG. 5 illustrates a stroke device having a revascularizationdevice 124″ coupled to a distal end of an inner catheter 122″. In oneembodiment, a revascularization device 124″ comprises one or moremarkers 125. The markers 125 can comprise at least one marker materialselected from the group consisting essentially of platinum and gold.With reference to FIG. 4B, one or more markers can be pressed intopre-laser cut apertures 126 designed to matingly embrace the same.

Catheter-revascularization system 100 is deployed through a patient'sblood vessels. Once the user of catheter-revascularization system 100determines that the embolus to be addressed is crossed, as known andunderstood well by artisans, revascularization device 124 is deployed byfirst positioning outer catheter 112 in a location immediately distal tothe embolus.

Then, to revascularize/reperfuse the occluded blood vessel, distalcatheter 120 is deployed in a location whereby revascularization device124 expands at the location of the embolus, as illustrated by FIG. 2.The embolus is thereby compressed against the luminal wall of the bloodvessel and blood flow is restored. Modular detachable segment 113 isknown also, and may be swapped out, as needed, if an Rx system is used.

As discussed above and claimed below, creating a channel for flowideally includes making a vessel at least about halfway-patent, or 50%of diameter of a vessel being open. According to other embodiments, thechannel created may be a cerebral equivalent of thrombolysis inmyocardial infarction TIMI 1, TIMI 2, or TIMI 3.

Restoration of blood flow may act as a natural lytic agent and manyemboli may begin to dissolve. Revascularization device 124 is designed,according to embodiments, to radially filter larger pieces of thedissolving embolus and prevent them from traveling distal to the deviceand potentially causing occlusion in another location. Because therevascularization device provides continuous radial pressure at thelocation of the obstruction, as the embolus dissolves, the blood flowcontinues to increase.

After the embolus is lysed, revascularization device 124 is sheathedinto outer catheter 112 and removed from the body. According toembodiments, larger pieces of the thrombus may be retracted withrevascularization device 124 after being captured in the radialfiltering process. According to embodiments, revascularization device124 may be detachable whereby the revascularization device 124 maydetach from catheter-based revascularization system 100 if it isdetermined that revascularization device 124 should remain in thepatient. As discussed above, illustrated in the Figures, and claimedbelow according to embodiments, catheter-based revascularization system100 reconstrainable attachment or attachment by tether may be optionallydetachable. Revascularization device detachment methods comprisemechanical, electrical hydraulic, chemical, thermal, and those otheruses known to artisans.

According now to FIG. 6, delivery tube 200 deploys tethered cage-likedevice/temporary stent 201 prior to embolization, using standardover-the-wire (OTW) system 199.

According to the disclosure, a temporary tethered cage-likestructure/tethered stent 201 is non-detachable in some embodiments butattached either to a hypotube or guide wire 199 allowing it to benavigated into tortuous vasculature in the brain. Device 201 may beattached to guide wire 199 or tube 200.

FIG. 7 likewise provides further details of the instant system, withtethered cage-like structure/temporary stent 201 being released fromdelivery tube 200 using known OTW techniques.

The delivery tube 200 is a variable stiffness tube that is able to trackto and through the tortuous anatomy or the cerebral vasculature (i.e.,internal carotid artery, MCA, ACA, vertebral and basilar).

The delivery tube 200 can be one or two pieces but must have greaterproximal pushability (stiffness) & greater distal flexibility (softness)to allow tracking to distal cerebral arteries.

The delivery tube 200 should also have a lumen that enables trackingover a guide-wire. This feature provides a few benefits; ability totrack and be delivered; ability to maintain access in the eventdifferent size devices need to be exchanged; provide support to arterialtree during device deployment and recovery. A flexible device may tendto herniate or prolapse into openings. The guide wire provides a pathway(concentric) to the artery and supports the device preventing suchtechnical complications.

The delivery tube 200 can be mechanically attached to the tethered stentby soldering, welding or press fitting. Likewise, those skilled in theart readily understand their attachment mechanisms.

The cage-like structure/stent is made of nitinol to allow it to becompressed and loaded into an introducer for packaging. Similarlymemory-based materials likewise function, in accordance with the instantsystems.

By attaching it to a delivery wire, the cage-like structure/stent can beplaced, retracted, repositioned and recaptured into a microcatheter.

FIGS. 8A-8D illustrate an embodiment of a revascularization device 800configured for eccentric coupling to a pusher. The revascularizationdevice 800 can be tethered to a pusher (e.g., wire or tube) by aplurality of tether lines 802 (also shown, for example, in FIGS. 2 and2A). In some embodiments, the revascularization device 800 iseccentrically coupled to the pusher (e.g., tethered off-center). Invarious embodiments, the revascularization device comprises an openproximal end and/or an open distal end and a generally cylindrical body(see, for example, FIGS. 2 and 2A, 4A-4C, and 5-7).

While the apparatus and method have been described in terms of what arepresently considered to be the most practical and preferred embodiments,it is to be understood that the disclosure need not be limited to thedisclosed embodiments. It is intended to cover various modifications andsimilar arrangements included within the spirit and scope of the claims,the scope of which should be accorded the broadest interpretation so asto encompass all such modifications and similar structures. The presentdisclosure includes any and all embodiments of the following claims.

It should also be understood that a variety of changes may be madewithout departing from the essence of the invention. Such changes arealso implicitly included in the description. They still fall within thescope of this invention. It should be understood that this disclosure isintended to yield a patent covering numerous aspects of the inventionboth independently and as an overall system and in both method andapparatus modes.

Further, each of the various elements of the invention and claims mayalso be achieved in a variety of manners. This disclosure should beunderstood to encompass each such variation, be it a variation of anembodiment of any apparatus embodiment, a method or process embodiment,or even merely a variation of any element of these.

Particularly, it should be understood that as the disclosure relates toelements of the invention, the words for each element may be expressedby equivalent apparatus terms or method terms—even if only the functionor result is the same.

Such equivalent, broader, or even more generic terms should beconsidered to be encompassed in the description of each element oraction. Such terms can be substituted where desired to make explicit theimplicitly broad coverage to which this invention is entitled.

It should be understood that all actions may be expressed as a means fortaking that action or as an element which causes that action.

Similarly, each physical element disclosed should be understood toencompass a disclosure of the action which that physical elementfacilitates.

Any patents, publications, or other references mentioned in thisapplication for patent are hereby incorporated by reference. Inaddition, as to each term used it should be understood that unless itsutilization in this application is inconsistent with suchinterpretation, common dictionary definitions should be understood asincorporated for each term and all definitions, alternative terms, andsynonyms such as contained in at least one of a standard technicaldictionary recognized by artisans and the Random House Webster'sUnabridged Dictionary, latest edition are hereby incorporated byreference.

Finally, all referenced listed in the Information Disclosure Statementor other information statement filed with the application are herebyappended and hereby incorporated by reference; however, as to each ofthe above, to the extent that such information or statementsincorporated by reference might be considered inconsistent with thepatenting of this/these invention(s), such statements are expressly notto be considered as made by the applicant(s).

In this regard it should be understood that for practical reasons and soas to avoid adding potentially hundreds of claims, the applicant haspresented claims with initial dependencies only.

Support should be understood to exist to the degree required under newmatter laws—including but not limited to United States Patent Law 35 USC132 or other such laws—to permit the addition of any of the variousdependencies or other elements presented under one independent claim orconcept as dependencies or elements under any other independent claim orconcept.

To the extent that insubstantial substitutes are made, to the extentthat the applicant did not in fact draft any claim so as to literallyencompass any particular embodiment, and to the extent otherwiseapplicable, the applicant should not be understood to have in any wayintended to or actually relinquished such coverage as the applicantsimply may not have been able to anticipate all eventualities; oneskilled in the art, should not be reasonably expected to have drafted aclaim that would have literally encompassed such alternativeembodiments.

Further, the use of the transitional phrase “comprising” is used tomaintain the “open-end” claims herein, according to traditional claiminterpretation. Thus, unless the context requires otherwise, it shouldbe understood that the term “comprise” or variations such as “comprises”or “comprising”, are intended to imply the inclusion of a stated elementor step or group of elements or steps but not the exclusion of any otherelement or step or group of elements or steps.

Such terms should be interpreted in their most expansive forms so as toafford the applicant the broadest coverage legally permissible.

1. A method of restoring blood flow through an obstructed blood vesselof the cerebral vasculature, comprising: identifying an obstructed bloodvessel within the cerebral vasculature of a patient, the obstructedblood vessel having an occlusive embolus; inserting a catheter-basedrevascularization system within the obstructed blood vessel; wherein thecatheter-based revascularization system comprises an outer catheter andan inner catheter longitudinally moveable with respect to each other;wherein the inner catheter comprises a pusher and a self-expandablerevascularization device eccentrically tethered to a distal end of thepusher; wherein the self-expandable revascularization device comprises agenerally cylindrical body having an open proximal end, an open distalend, and a plurality of struts that form a plurality of cells betweenthe proximal and distal ends; positioning the outer catheter at alocation distal to the embolus; retracting the outer catheter to deploythe self-expandable revascularization device at the location of theembolus thereby compressing the embolus against a luminal wall of theblood vessel and restoring flow through the blood vessel; wherein therestored blood flow facilitates natural lysis of the embolus; whereinthe natural lysis and compression of the embolus cause fragmentation ofat least a portion of the embolus into a plurality of embolic fragments,wherein one or more of said embolic fragments pass through the opendistal end of the self-expandable revascularization device downstream ofthe embolus; and wherein the self-expandable revascularization deviceexerts continuous radial pressure at the location of the embolus tofurther facilitate blood flow through the blood vessel as the emboluslyses; resheathing the revascularization device within the outercatheter; and removing the revascularization system from the patient. 2.The method of claim 1, wherein the revascularization device ispermanently tethered to a distal end of the pusher.
 3. The method ofclaim 1, wherein the revascularization device is detachably tethered toa distal end of the pusher.
 4. The method of claim 1, wherein therevascularization device comprises radiopaque markers configured fortracking of the revascularization device.
 5. The method of claim 4,further comprising tracking the revascularization device to confirmproper positioning with respect to the embolus.
 6. The method of claim1, wherein deploying the self-expandable revascularization device at thelocation of the embolus comprises creating an immediate flow channelwithin the blood vessel of at least about 50% of the diameter of theblood vessel of the cerebral vasculature.
 7. The method of claim 1,wherein the pusher comprises a variable-pitch hypotube.
 8. The method ofclaim 1, wherein the pusher comprises a wire.
 9. The method of claim 1,wherein at least a portion of said inner catheter comprises a flexiblematerial configured to permit flexion and extension to navigate throughcurved vessels of the cerebral vasculature.
 10. The method of claim 1,further comprising infusing lytic agents to the location of the embolusthrough the revascularization system.
 11. The method of claim 1, furthercomprising removing at least a portion of the embolus captured by therevascularization device.
 12. The method of claim 1, wherein therevascularization device comprises a self-expanding microstent.
 13. Themethod of claim 1, further comprising morselizing at least a portion ofthe embolus by mechanical manipulation of the revascularization device.14. The method of claim 1, wherein inserting the catheter-basedrevascularization system within the obstructed blood vessel comprisesadvancing the revascularization system over a guidewire proximate alocation of the embolus.
 15. A method of restoring blood flow through anobstructed blood vessel of the brain to treat acute ischemic stroke,comprising: identifying an obstructed blood vessel within the cerebralvasculature of a patient, the obstructed blood vessel having an embolus;inserting a catheter-based revascularization system within theobstructed blood vessel; wherein the catheter-based revascularizationsystem comprises an outer catheter and an inner catheter longitudinallymoveable with respect to each other; wherein the inner cathetercomprises a pusher and a self-expandable revascularization devicetethered to a distal end of the pusher; wherein the self-expandablerevascularization device comprises an open proximal end, an open distalend, and a plurality of struts that form a plurality of cells betweenthe proximal and distal ends; positioning the outer catheter at alocation distal to the embolus; retracting the outer catheter, therebydeploying the self-expandable revascularization device at the locationof the embolus, thereby compressing the embolus or lesion against aluminal wall of the obstructed blood vessel and restoring flow throughthe obstructed blood vessel; wherein the restored blood flow facilitatesnatural lysis of the embolus; wherein the natural lysis and compressionof the embolus cause fragmentation of at least a portion of the embolusinto a plurality of fragments, wherein one or more of said fragmentspass through the open distal end of the self-expandablerevascularization device downstream of the embolus; and wherein theself-expandable revascularization device exerts continuous radialpressure at the location of embolus to further facilitate blood flowthrough the blood vessel as the embolus lyses; resheathing therevascularization device within the outer catheter; and removing therevascularization system from the patient.
 16. The method of claim 15,wherein the self-expandable revascularization device is generallycylindrical and eccentrically tethered to the distal end of the pushervia a plurality of tethered lines.
 17. The method of claim 15, furthercomprising morselizing at least a portion of the embolus by mechanicalmanipulation of the revascularization device.
 18. The method of claim15, further comprising removing at least a portion of the emboluscaptured by the revascularization device.
 19. The method of claim 15,wherein deploying the self-expandable revascularization device at thelocation of the embolus comprises creating an immediate flow channelwithin the blood vessel of at least about 50% of the diameter of theblood vessel of the cerebral vasculature.
 20. The method of claim 15,wherein inserting a catheter-based revascularization system within theobstructed blood vessel comprises advancing the revascularization systemover a guidewire proximate a location of the embolus.